Essay On Urban Trees

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Increase in fossil fuel combustion has altered atmospheric composition over last century and more so in urban areas where air quality has generally deteriorated. Pollutants, like ozone (O3), carbon monoxide (CO), nitrogen oxides (NOx), sulphur dioxide (SO2), heavy metals, volatile organic compounds (VOCs) and particulate matter (PM2.5 and PM10) have varied composition, properties, emission rates, degeneration time and diffusion potential. Urban trees being near to the emission sources have a positive effect on local air quality. Trees when properly selected and managed, have potential to improve quality of urban air (Nowak, 2000).
Oxygen production is the most commonly cited benefit of trees but Nowak et al. (2007) opined that considering the large amount …show more content…

Highest pollutant levels have been recorded within the range of 100 to 150 meters of highways and remain high up to 300 to 500 meters or even more (Karner et al., 2010). It has been projected that nearly 30-45 per cent of people in US cities live within high pollutant zones of the roads. Strong evidence has been found between traffic generated air pollution and asthma flare up. Incidence of childhood asthma, other respiratory disorders, cardiovascular diseases have also been found to increase in the polluted zones and traffic associated pollution has emerged as a major public health issue which deserves serious attention (HEI, 2010).
Broadleaf trees have been reported to be more efficient in pollution removal than conifers. Seasonal variation between types of leaves, their arrangement and physiology have also been observed (Alonso et al., 2011). Vegetation barriers along roads effectively reduce air pollution. Lower concentration of pollutants has been recorded downwind of trees along highways. Planting large sized trees after construction had immediate impact on pollution levels (Baldauf et al.,

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